Switch LibraryProvider from a Monitor to a ReaderWriterLockSlim

src/J.Core/LibraryProvider.cs

@@ -19,9 +19,8 @@ public sealed partial class LibraryProvider : IDisposable
     private readonly AsyncRetryPolicy _policy = Policy
         .Handle<Exception>(x => x is not AmazonS3Exception s3ex || (int)s3ex.StatusCode >= 500)
         .RetryAsync(5);
-    private readonly object _lock = new();
+    private readonly ReaderWriterLockSlim _rwlock = new();
     private SqliteConnection? _connection;
-    private bool _inTransaction;
 
     public LibraryProvider(AccountSettingsProvider accountSettingsProvider, ProcessTempDir processTempDir)
     {
@@ -37,9 +36,35 @@ public static void Create(string filePath)
         connection.Open();
     }
 
+    private void WithWriteLock(Action action)
+    {
+        _rwlock.EnterWriteLock();
+        try
+        {
+            action();
+        }
+        finally
+        {
+            _rwlock.ExitWriteLock();
+        }
+    }
+
+    private T WithReadLock<T>(Func<T> func)
+    {
+        _rwlock.EnterReadLock();
+        try
+        {
+            return func();
+        }
+        finally
+        {
+            _rwlock.ExitReadLock();
+        }
+    }
+
     public void Connect()
     {
-        lock (_lock)
+        WithWriteLock(() =>
         {
             _connection?.Dispose();
             _connection = null;
@@ -53,16 +78,16 @@ public void Connect()
             Execute("PRAGMA foreign_keys = ON;");
 
             Upgrade();
-        }
+        });
     }
 
     public void Disconnect()
     {
-        lock (_lock)
+        WithWriteLock(() =>
         {
             _connection?.Dispose();
             _connection = null;
-        }
+        });
     }
 
     public void Dispose()
@@ -137,7 +162,7 @@ private List<T> Query<T>(
         Func<SqliteDataReader, T> generator
     )
     {
-        lock (_lock)
+        return WithReadLock(() =>
         {
             using var command = _connection!.CreateCommand();
             command.CommandText = sql;
@@ -147,7 +172,7 @@ Func<SqliteDataReader, T> generator
             while (reader.Read())
                 rows.Add(generator(reader));
             return rows;
-        }
+        });
     }
 
     private T QuerySingle<T>(
@@ -161,13 +186,13 @@ Func<SqliteDataReader, T> generator
 
     private void Execute(string sql, Action<SqliteParameterCollection>? configureParameters = null)
     {
-        lock (_lock)
+        WithWriteLock(() =>
         {
             using var command = _connection!.CreateCommand();
             command.CommandText = sql;
             configureParameters?.Invoke(command.Parameters);
             command.ExecuteNonQuery();
-        }
+        });
     }
 
     public void NewTagType(TagType tagType) =>
@@ -578,33 +603,14 @@ FROM tags
         );
     }
 
-    public bool InTransaction
-    {
-        get
-        {
-            lock (_lock)
-            {
-                return _inTransaction;
-            }
-        }
-    }
-
     public void WithTransaction(Action action)
     {
-        lock (_lock)
+        WithWriteLock(() =>
         {
             using var transaction = _connection!.BeginTransaction();
-            _inTransaction = true;
-            try
-            {
-                action();
-                transaction.Commit();
-            }
-            finally
-            {
-                _inTransaction = false;
-            }
-        }
+            action();
+            transaction.Commit();
+        });
     }
 
     public async Task SyncUpAsync(CancellationToken cancel)